About 1,900 inmates are being freed across the US this week following a federal policy change that is easing sentencing rules for crack cocaine possession.

The new law lessens the sentencing by at least three years, a change meant to bring penalties surrounding the drug closer to those meted out for powder cocaine users.

The disproportionate penalties between the two drugs originated from fears that crack cocaine was more addictive than its powder form and linked to more violent crime. The distinction has subsequently been debunked and has been criticized for being racist, as powder cocaine users tend to be white.

Congress passed the change, titled the Fair Sentencing Act, last year. The US Sentencing Commission voted in June to make the law retroactive for prisoners currently in prison waiting out sentences based on the former sentencing rules. The reason, said US Sentencing Commission Chair Judge Patti Saris, was to recognize "the fundamental unfairness of federal cocaine sentencing policy."

Although the policy change was made last summer, Tuesday marked the first day prisoners could get immediate release from federal prison. About 12,000 prisoners will be released over the next three years; 1,900 of those are eligible for release immediately.

One former inmate, Antwain Black, returned to his home in Springfield, Ill., Tuesday after serving over eight years in a federal prison in Leavenworth, Kan., for dealing crack cocaine. Mr. Black was originally scheduled to end his prison term in October 2013.

He told the Associated Press Tuesday that the former sentencing rules unfairly targeted black defendants.

"I didn't think it was fair and I still don't think it's fair … I know guys who aren't coming home, still, because of these laws that were placed upon a certain race of people," he said.

Under the revised policy, a federal judge must approve the reductions from a list prepared by the public defender's office while federal prosecutors can object based on the defendant's prior conduct. The reductions are expected to happen without new hearings.

The US Federal Bureau of Prisons says there is not yet data on exactly how many former inmates are being released this week, but ancillary reports from various public defender's offices suggest that the procedure to secure the early releases is swift.

In St. Louis, about 50 people are expected to walk free by Wednesday. The eastern district of Virginia will release about 75 people, while San Antonio, Texas, is releasing at least 20.

The revised sentencing rules mean that, in order to receive the minimum sentencing of five years, a person needs to possess 28 grams of crack cocaine, an increase from 5 grams. The 10-year sentencing requires 280 grams, an increase from 50 grams.

Despite the new change, there remains disparity in sentencing rules between both forms of cocaine: a 5-year powder cocaine conviction requires offenses involving 500 grams.

The new restrictions are for federal offenses only; people found guilty of crack cocaine offenses under state laws are not eligible for early release.

While the sentencing revisions are perceived as a way to undo an injustice laced with a racial undertone, Ryan Scott, a law professor at the Maurer School of Law at Indiana University in Bloomington, says the Congressional Black Caucus originally supported the earlier sentencing legislation as it was seen as a way to prevent further erosion of the country's inner-city neighborhoods.

"It wasn't exclusively intended as a way of punishing black offenders. There was real concern about the victims as well," Mr. Scott told the Journal Gazette in Fort Wayne, Ind.